Lettuce Diseases and their Management

Abstract

Lettuce is the world's most popular leafy salad vegetable. Various types of lettuce are cultivated across the globe, primarily for human consumption of their fresh, succulent leaves. Over 75 lettuce disorders of diverse causes and etiologies have been described. While some diseases are limited in their importance and distribution, a significant number are present wherever Lactuca sativa L. is grown. Many are capable of causing devastating losses in yield and quality under favorable conditions. In this chapter, we have divided lettuce diseases broadly into infectious and non-infectious disorders. Of the important infectious diseases covered, fungi and viruses account for the bulk. Nine fungal diseases are discussed, including anthracnose, bottom rot, Cercospora leaf spot, damping-off, downy mildew, drop, gray mold, Septoria leaf spot, and southern blight. Five viral diseases are covered, and these are: beet western yellows, lettuce big-vein, lettuce infectious yellows, lettuce mosaic, and tomato spotted wilt. The sole phytoplasmic lettuce disease, aster yellows, is also discussed. Of five important bacterial diseases detailed, four are foliar disorders: bacterial leaf spot, marginal leaf blight, soft rot, and varnish spot. Corky root is the one bacterial root disease included. In contrast, all nematode pathogens discussed, lesion, needle, and root-knot nematodes, infect lettuce roots. Three important non-infectious disorders are included in this chapter, namely brown stain, pink rib, and tipburn. These are mainly disorders of mature or postharvest lettuce. Lettuce typesThere are a number of different types of lettuce, including: crisphead (iceberg), romaine (cos), leaf, butterhead (Boston and bibb), and numerous others of limited popularity. These include Latin, Batavia, stem, and oilseed types (Ryder 1979).

Nematicidal Activity of Pyrolisate of Bambusa vulgaris on Root-Knot Nematode; Meloidogyne incognita of Lettuce

“…In Nigeria, Lettuce is generally considered an important exotic vegetable crop and its increased production was attributed to the increasing awareness about its health and nutritional benefits (Ogbodo et al, 2010;Shuaibu and Mohammed, 2018). Lettuce like many other vegetable crops is susceptible and severely affected by the root-knot nematodes causing substantial yield losses thereby posing a significant threat to its production worldwide (Raid, 2004;Fabiyi, 2022). Growers most times resort to the use of synthetic chemical nematicides in managing this economically important pest (Fabiyi and Bello, 2023).…”

Preemergence and postemergence spiny amaranth (Amaranthus spinosus) and common lambsquarters (Chenopodium album) control in lettuce on organic soils

“…The crop is planted at shallow depth because of the small seed size. After lettuce planting, fields are sprinkler irrigated until emergence, and thereafter, subsurface irrigated by raising the water table along ditches and canals surrounding the fields (Snyder et al 1978) to minimize leaf wetness and assist in mitigating occurrence of foliar diseases (Raid 2004). These practices provide ideal conditions for weeds to emerge simultaneously with lettuce.…”

Salts as Controlling Agents of Lettuce Leaf Spot Diseases

“…It is an important dietary crop available that contains phenolic compounds, carotenoids such as carotene and vitamin E (Nicollec et al, 2004). Lettuce is the world's most popular vegetable salad produced commercially in many countries worldwide and exclusively used as a fresh vegetable in salads, but some forms are also cooked (Raid, 2004, Lebeda et al, 2007. Bradley et al (2009) reported that 16 fungal diseases were the most important, prevailing problems on lettuce under greenhouses conditions.…”